Recognizing specific molecules and reporting their presence in a complex mixture is a significant challenge, and this proposal outlines a new supramolecular approach to address this problem. There has been a great interest in detecting biomarkers in small concentrations in physiological fluids, such as serum, because of the implications in early detection of diseases. In this proposal, we focus on peptide- and protein-based biomarkers, the detection of which is of interest in the early diagnosis of cancer - a criticl factor in effective cancer treatment. The preliminary results are very encouraging and it is essential that we further develop this approach for real-life systems by understanding the factors that underlie the binding and detection events. The proposed research is focused on this purpose. The key elements of our approach are that: (i) our polymer assemblies are kinetically trapped in the assembled solvent and maintain their supramolecular fidelity under a broad range of conditions; (ii) these assemblies bind to a selective set of peptides to move them from the aqueous to the organic phase; (iii) our polymers provide signal enhancements that greatly enhance the sensitivity of detection; and (iv) the proposed experimental protocols allow for concurrent detection of several biomarkers sensitively. These promising features will be rigorously tested for detecting cancer biomarkers in complex physiological fluids, serum and breast milk. Note that we focus on well-established cancer biomarkers to allow us to focus squarely on testing the versatility of new approach.